Liquid thermosetting resin composition, printed wiring boards and process for their production

Abstract

A liquid thermosetting resin composition comprises (A) an epoxy resin, (B) a curing catalyst, and (C) a filler and is characterized by exhibiting a viscosity at 25° C. of not more than 1,500 dPa.s, a gel time of not less than 300 seconds at a temperature at which the composition exhibits a melt viscosity of not more than 10 dPa.s, and a gel time at 130° C. of not more than 600 seconds. In the production of a printed wiring board by superposing an interlaminar resin insulating layer and a conductive circuit on the surface of the wiring board having a conductive circuit pattern including hole parts, a hole filling process is performed by filling the hole parts mentioned above with the composition mentioned above, effecting precure of the composition by heating, then polishing and removing parts of the precured composition protruding from a surface defining the hole parts, and further heating the precured composition till final curing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of Application PCT / JP01 / 09955, filed Nov. 14, 2001, now abandoned.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to a liquid thermosetting resin composition, particularly a liquid thermosetting resin composition which is useful as a composition for permanently filling such holes as via holes and through-holes in printed wiring boards or printed circuit boards such as multi-layer boards and double-sided boards. The liquid thermosetting resin composition of the present invention may also be used as various resists, interlaminar insulating materials, sealing compounds for IC packages, and the like.[0004]The present invention further relates to a printed wiring board whose holes such as via holes and through-holes have been permanently filled by the use of the composition mentioned above and a process for the production thereof.[0005]Incidentally, the term “hole part” as used in t...

AI Technical Summary

Benefits of technology

[0025]By the process as described above, it is possible to effect the filling of holes such as via holes and through-holes of a printed wiring board with the composition with high operational efficiency and to produce with high productivity a highly reliable printed wiring board which is excellent in various properties such as insulating

Problems solved by technology

In this process for permanently filling holes in a printed wiring board, when the hole parts such as through-holes and via holes of the printed wiring board are filled with the epoxy resin composition, the filled composition inevitably gives rise to voids due to such phenomena as air entrapment.

It was hardly possible to completely remove or vanish such voids even when the precure and the final cure are performed.

Further, in the process for permanently filling holes in a printed wiring board mentioned above, there was another problem of the occurrence of cracks during the step of precure.

Moreover, there was another problem that the composition shrinks largely during the course of thermal curing and the finally cured comp

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